I'm dealing with a hydrological landscape that is extensively diked, culverted, and otherwise modified/managed (for irrigation), and which has multiple parallel river channels in many places. Consequently, my attempts to create, for instance, a watershed for the system (the existing HUC for the area shows significant error) gives me very disappointing results (think "watersheds" ~30m long). I'd also like to be able to model flow accumulation and impoundment effects behind dikes given the capacities of the outlet culverts/control structures. Is there a way to reflect these factors in a hydrology DEM?
Basically, we're using the same irrigation system as the Mesopotamians (i.e., controlled seasonal field inundation), and I'd like to be able to model how well it functions. The data I have includes a 10m DEM for the whole watershed, points for the various water management structures, dike polylines, and a pretty detailed and accurate NWI polyline set. Ideally, I'd be able to simulate a few different irrigation scenarios and have a baseline model for comparison.
Any help is appreciated!